1. Field of the Invention
The present invention relates to optics units, and in particular relates to optics units used in vehicular lighting fixtures.
2. Description of the Related Art
Optics units furnished with a rotary reflector that rotates unidirectionally about its rotational axis while reflecting light emitted from a light source are known (see JP2010-092124). Circumferentially with respect to its rotational axis the rotary reflector is provided with a plurality of blades provided with reflective surfaces whereby reflected light forms a desired light-distribution pattern. An advantage of this sort of optics unit that can form a desired light-distribution pattern by the unidirectional rotation of the rotary reflector is that load on the reflector's rotational driving unit is slight.
With the optics unit described in JP2010-092124, the rotary reflector is made to function as a cooling fan that through the rotation of the blades promotes heat dissipation by giving rise to convection currents in the air near a heat dissipation unit of the light source. Nevertheless, the airflow produced by the blades turns out to be directed parallel to the rotary reflector's rotational axis, meaning that the majority of the flow misses the heat dissipation unit, which is prohibitive of yielding sufficient cooling effectiveness.